On 12.12.23 11:13, Heinrich Schuchardt wrote:
On 12.12.23 09:52, [email protected] wrote:
From: Lukas Funke <[email protected]>
This series enables the 'setexpr' command to print "cpu list"-like
bitmaps based on the printk format specifier [1].
One use-case is to pass cpu list [2] based kernel parameter like
'isolcpu', 'nohz_full', irq affinity or RCU related CPU parameter to
the kernel via a separate firmware variable without exposing the
'bootargs' variable to directly.
Example:
setexpr isolcpu_bootarg=%32pbl $myCPUisolation
I applied your patches on top of origin/next but your example simply
does not work:
=> setenv myCPUisolation 123456789abcdef0
=> setexpr isolcpu_bootarg=%32pbl $myCPUisolation
## Error: illegal character '='in variable name "isolcpu_bootarg=%32pbl"
This produces some output:
=> setexpr a fmt '%32pbl' 64; echo $a
6
But the result is completely unexpected. Number arguments in U-Boot are
always hexadecimal. So the output should be
2,5-6
doc/usage/cmd/setexpr.rst
has an example showing this.
=> setexpr foo fmt 0x%08x 63
=> echo $foo
0x00000063
=>
You provide a use case for %pbl but not an reason why you want to
support %pb. If you wanted to use the output in a device-tree
manipulation the %pb output would have to be big-endian formatted.
Best regards
Heinrcih
&& env set bootargs "$isolcpu_bootarg"
&& bootm
[1] https://www.kernel.org/doc/Documentation/printk-formats.txt
[2]
https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html
Changes in v2:
- Add bitmap format specifier to documentation
Lukas Funke (6):
sandbox: add generic find_next_zero_bit implementation
linux: bitmap.h: add 'for_each_set_bitrange' iteration macro
test: cmd: setexptr: Add tests for bitmap string format
doc: printf() codes: Add bitmap format specifier
lib: vsprintf: enable '%*pb[l]' format specifier
cmd: printf: forward '%p' format string specifier
arch/sandbox/include/asm/bitops.h | 16 ++++++-
cmd/printf.c | 29 ++++++++++++
doc/develop/printf.rst | 6 +++
include/linux/bitmap.h | 7 +++
lib/vsprintf.c | 75 +++++++++++++++++++++++++++++++
test/cmd/setexpr.c | 9 ++++
6 files changed, 140 insertions(+), 2 deletions(-)
